Thinly slice the shallots and heat vegetable oil in a deep skillet. Fry the shallots for about 4-5 minutes until golden brown and crispy.

In a large pot, bring water to a boil and add salt. Blanch the green beans for 3-4 minutes until tender yet bright green.

In the same skillet, melt 4 tablespoons of unsalted butter. Add minced garlic and sauté until fragrant. Incorporate sliced mushrooms and cook until tender.

Gradually whisk in cream or milk into the mushroom mixture, stirring continuously until thick and creamy. Fold in the blanched green beans and half of the Parmesan cheese.

Sprinkle remaining Parmesan cheese and a layer of fried shallots over the green beans. Preheat oven to 375°F and bake covered for 20 minutes, then uncover for an additional 7-10 minutes until golden.